1. Field of the Invention
The present invention relates to an apparatus and method for inspecting a liquid crystal display panel, and more particularly to an apparatus and method that improves the reliability of the inspection process.
2. Description of the Related Art
A liquid crystal display (LCD) device displays a picture in response to image signals by controlling the amount of light transmitted through the device. Because of the characteristics of the LCD device, such as light weight, thin body, and low power consumption, the application of LCD devices continues to increase. LCD devices are commonly used in office automation equipment, notebook computers, and the like.
Continued advances in LCD technology in the areas of screen size, high definition and low power consumption have lead to the rapid replacement of cathode ray tubes with LCD panels. As a result of research and development and mass production technology, active matrix LCD devices that provide excellent picture quality and low power consumption are being developed with larger display size and higher resolution.
Manufacturing methods for active matrix liquid crystal display devices include a substrate cleaning process, a substrate patterning process, an alignment forming/rubbing process, a substrate bonding/liquid crystal injection process, an inspection process, a repair process, and a mounting process.
The substrate cleaning process removes impurities which may contaminate the substrate surface of the liquid crystal display device. The substrate patterning process generally includes an upper substrate patterning process and a lower substrate patterning process. For example, during the upper substrate patterning process a common electrode and a black matrix are formed. During the lower substrate patterning process, for example, signal lines such as data and gate lines and the like are formed. Furthermore, a thin film transistor(TFT) is formed at a intersection of the data line and the gate line, and a pixel electrode is formed at a pixel region defined between the data line and the gate line, wherein the data line is connected to a source electrode of the TFT.
During the alignment film forming/rubbing process an alignment film is coated onto the upper and lower substrate and the alignment direction of the alignment film is formed, for example, by rubbing the alignment film with a rubbing cloth.
During the substrate bonding/liquid crystal injection process the upper substrate and the lower substrate are sealed together and a liquid crystal material and spacers are injected between the substrates through an injection hole forming a liquid crystal panel.
The inspection process includes an electrical inspection that is conducted after the signal lines and pixel electrode are formed on the substrate, and an electrical and naked-eye inspection that is conducted after the substrate bonding/liquid crystal injection process is completed.
During the repair process a determination is made as to whether the substrates that failed the inspection process are repairable.
During the mounting process a tape carrier package TCP comprising integrated circuits such as a gate drive IC and a data drive IC mounted thereon is connected to the liquid crystal panel. The integrated circuits may also be directly mounted on the substrate using a chip-on-glass(COG) technique or a tape automated bonding(TAB) technique using the TCP.
FIG. 1 illustrates an auto probe inspecting device 60 used during the inspection process. As illustrated in FIG. 1, the auto probe inspecting device 60 comprises a probe unit 10 and a back light unit BU.
The probe unit 10 provides signals from a generator and a controller (not shown) for driving the liquid crystal panel during the inspection process. The probe unit 10 includes: a probe base 14 having a hole in which the liquid crystal panel to be inspected is inserted; a printed circuit board(PCB) base 18 installed at adjacent edges of the probe base 14; a plurality of TCP blocks 16 connected to the PCB base 18; and a plurality of probe blocks 12 connected to the TCP blocks 16. In addition, each probe block 12 has a manipulator 24 that reduces the collision and friction forces generated upon installing the liquid crystal panel 2 in the probe unit 10.
The back light unit BU includes: back lights 20 that irradiate light on a rear surface of the liquid crystal panel 2; and a back light housing 22 on which the back lights 20 are secured.
A method of inspecting the liquid crystal panel 2 using the auto probe inspection device 60 according to the related art is as follows. First, the liquid crystal panel 2 is inserted into the hole of probe unit 10 such that the manipulators 24 engage the edge and corner of the liquid crystal panel 2 and contact is made between the pads 26 of the liquid crystal panel 2 and probe blocks 12. The back lights 20 receive power from a power source (not shown) and generate light that is transmitted to the liquid crystal panel 2. Thereafter, inspection signals generated from a signal driver and controller (not shown) are switched to each TCP block 16 through the PCB base 18. The inspection signals are transmitted through the TCP block 16 to pads 26 of the liquid crystal panel 2 via the probe block 12 and are then supplied to the signal lines connected to the pads 26. A worker checks for bad pixels generated on the liquid crystal panel, as well as, inspects the pixel driving of the liquid crystal panel in accordance with a signal control of the signal driver using the naked-eye.
Accordingly, in the related art inspection method determination of a bad pixel is based on the vision of the work. This results in errors during the inspection process depending upon the health and eye condition of the worker performing the inspection. Furthermore, the eyes are susceptible to fatigue when exposed to light rays. Thus the light generated from the back light 20 increases visual fatigue in the worker. Accordingly, there is a problem in that the reliability of the inspection result is decreases because result is not uniform.
Further, since the back light 20 employs a line light emission not a surface light emission, the light generated from the back light 20 is not uniformly incident to the entire surface of the liquid crystal panel 2. Accordingly, illumination at the center of the liquid crystal panel is different from the illumination at the edge of the liquid crystal panel. As a result, the liquid crystal panel is not uniformly illuminated.